Mosquitoes in the genus Culex are major vectors of human diseases throughout the world. In the U.S. Culex mosquitoes have been identified as the principal vectors of West Nile Virus (WNV). The research activities described in this proposal combine the expertise of medical entomologists, molecular biologists, chemical/behavioral ecologists and biochemists from the University of California, Davis and UC, Riverside campuses; operational specialists from the Coachella Valley, Greater Los Angeles, Merced County and Shasta County Mosquito and Vector Control Districts, and industry partners from the Bayer Environmental Science, Bedoukian Research and Syngenta corporations. The overall goal is to improve strategies to control Culex mosquitoes by modifying methods for the application of chemical insecticides, developing novel methods for monitoring metabolic resistance to these insecticides and the development of improved methods for trapping gravid Culex mosquitoes. This research is aimed at increasing our capacity to effectively manage Culex populations in the near term; not twenty years hence. Current emergency WNV control programs are focused largely on Culex and have had mixed results. They have failed to prevent virus transmission, and have brought into question the efficacy of current control strategies. Under Aim #1 we will provide a rigorous evaluation of conventional insecticide application methodologies and of a novel strategy involving the application of focused barrier treatments of vegetation in which host seeking Culex mosquitoes are known to congregate. Under Aim #2 we will develop methods to more accurately detect and qualitatively measure enzyme mediated pyrethroid insecticide resistance. We propose to achieve this by developing novel pyrethoid-like fluorescent substrates for detection of P450 mixed function oxidases and esterases in Culex mosquitoes. These new substrates are highly sensitive. They will be developed for microplate assays that are rapid and inexpensive, but produce highly quantitative and selective results for detecting pyrethroid P450 mixed function oxidase and esterase activity in individual mosquitoes. For the surveillance and integrated management of the vectors of WNV and other important viruses in urban and peri-urban environments, selective semiochemical-based mosquito traps are essential but current trapping technology demands much improvement. Under Aim #3 we will work to optimize trap efficacy through the development of better lures. Candidate attractants including a homochiral "oviposition attractant" will be evaluated and chemical prospecting for novel attractants will be conducted using state-of-the-art approaches. We will mount a multidisciplinary effort in which activity of potential lures will be assessed by sensory physiology (electrophysiology), flight observations (wind tunnel and videography) and a molecular approach based on affinity to a carrier protein (odorant binding protein).